Samsung 100737108-A ,

Spinpoint M8-DVR OEM Product Manual REV 1.0

5.4.2 The Write Channel

The signal path for the Write Channel follows the reverse order of that for the Read Channel. The host transmits

data via the AT bus to the 88i9422 Interface Controller. The Buffer Controller section of the 88i9422 stores the

data in the cache. Because the data is transmitted to the drive at a rate that exceeds the rate at which the drive can

write data to the disk, data is stored temporarily in the cache. Thus, the host can present data to the drive at a rate

independent of the rate at which the drive can write data to the disk.

Upon correct identification of the target address, the data is shifted to the Sequencer, which generates and appends

an error correcting code. The Sequencer then converts the bytes of data to a serial bit stream. The AT controller

also generates a preamble field, inserts an address mark, and transmits the data to the ENDEC in the R/W IC where

the data is encoded into the LDPC format and pre-compensates for non-linear transition shift. The amount of

write current is set by the 88i9422 DSP and Interface/Disk Controller through the serial interface to the

preamplifier.

The 88 i9422 switches the Preamplifier and Write Driver IC to write mode and selects a head. Once the

Preamplifier and Write Driver IC receive a write gate signal, it transmits current reversals to the head, which writes

magnetic transitions on the disk.

This section describes the following f irmware features:

 Read Caching

 Write Caching

 Track Skewing

 Defect Management

 Automatic Defect Allocation

 ECC Correction

 SMART (Self-monitoring and reporting technology)

 ATA security mode features

 ATA host protected area

 ATA streaming features

 ATA power up in stand by feature set

 ATA advanced power management (APM) feat u re set

 ATA device configuration overlay (DCO) fe ature set

The Spinpoint M8 hard disk drive uses Read Cache to enhance drive performance and significantly improve

system throughput. Use the SET FEATURES command to enable or disable Read Caching. Read caching

anticipates host-system requests for data and stores that data for faster future access. When the host requests a

certain segment of data, the cache feature utilizes a prefetch strategy to get the data in advance and automatically

read and store the following data from the disk into fast RAM. If the host requests this data, the RAM is accessed

rather than the disk.

There is a high probability that subsequent data requested will be in the cache, because more than 50 percent of all